Propeller deicing control system



H. M- GEYER ETAL PROPELLER DEICING CONTROL SYSTEM Filed July 20, 1948 IN V EN TORS Ho Ward M Gaye?! 1 By 'Howard Carson. 2 f6 y 11, 1954 H. M. GEYER ETAL 2,678,181

PROPELLER DEICING CONTROL SYSTEM Filed July 20, 1948 4 Sheets--Sheet 2 .52 ,e 7 INVENTORS J H0 Wd rd M 683 87: 3 BY Howard Carson.

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May 11, 1954 H. M. 'GEYER ETAL PROPELLER DEICING' CONTROL'SYSTEM a; o 5 w s v% a MGM m mn NJ 0 m i w e d MW ,H 4 4 HH m E m Filed July 20, 1948 May 11, 1954 H. M. GEYER ETAL 2,678,181

PROPELLER DEICING CONTROL SYSTEM Filed July 2 1948 4 Sheets-$heet 4 INVENTORS Ha ward M Geyer:

BY Howard Carson.

THE/R FITTORN vs Patented May 11, 1954 PROPELLER DEICING CONTROL SYSTEM Howard M. Geyer, Dayton, Ohio, and Howard Carson, Seattle, Wash., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 20, 1948, Serial No. 39,624

3 Claims.- 1

This invention relates to the prevention and removal of ice formation on movable elements such as the blade elements of an aircraft propeller.

One object of the invention-is to effect the freedom of blade elements from ice formations that would materially affect the proper and efficient working of a propeller for aircraft.

Another object of the invention is toprevent the formation of ice on airfoil sections of aircraft so that the particular sections may function within the specificationsprescribed for them Without being disturbed by non-controllable influences.

Yet another object of the invention is to remove ice from airfoil sections that may have accumulated without notice or during an unguarded period, so that noncontrollable influences may be eliminated, and the airfoil section, maintained at the prescribed efficiency of operation such as dynamic balance.

Still another object of the invention is to control the formation of ice upon airfoil sections by the use of an electric current in such manner that the balance of related airfoil sections is not disturbed.

A further object of the invention is the control of ice formations on airfoil sections and the like by successive pulses of electric current, that effect a localized heating of the airfoil section suihcient to prevent the formation of ice thereon as to cause removal of ice if it has formed.

It is also another object of the invention to control the icing conditions of a group or plus rality of airfoil sections, that each section will be recipient of an equal amount of control so that if the plurality of sections are arranged in a symmetrical or balanced relation, that symmetry or balance will not be disturbed by more control of one section than of either of the other 7 associated. sections.

Thus, an important object of the invention is to provide control of icing conditions on a pinrality of pitch shiftable blade elements for a rotatable propeller in such fashion that all blade elements will be controlled equally, and so that if the control for one blade is interrupted for any reason, then the control for all other blades will also be cut off, thus retaining under all conditions the engineered balance of the entire propeller.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a wiring diagram of one system of icing control for an aircraft propeller where there are three blades served in parallel.

Fig. 2 is a simplified wiring diagram of an alternate system of icing control for a similar propeller but where the blades are served in series.

Figs. 3 and 4 are modifications respectively of Figs. 1 and 2, where the energizing source for the icing control is from'a propeller mounted generator or alternator. replacing the ships electrical system, Fig. 3 being a circuit diagram for serving the blades in parallel, and Fig. 4 being a circuit diagram for serving the blades in series.

Fig. 5 is a sectional view of a structural form of embodiment, it being the forward portion of a propeller mechanism integrally joined to the showing in Fig. 6 as indicated by the broken line made up of long dashes and dots.

Fig. 6 is a sectional View of the same structural form joined at the left to the structural form-shown in Fig. 5 as indicated by the broken line made up of long dashes and dots, the two Figs. 5 and 6, when joined representing a longitudinal section through an aircraft propeller assembly.

Fig. '7 is a detail in section showing a physical means of transferring the electrical energy to the blade, it being a section substantially as indicated by the line and arrow 1-! of Fig. 5.

Fig. 8 is a detail in elevation of the gear connections for drive of the alternator, it being a view suggested by the line and arrows B-3 of Fig. 6.

Electric icing control of airfoil sections offers many advantages over those systems depending upon inflation of pouches or tubes, distribution of low freezing-point fiuids, hot air delivery to the inside of structures and the like, since installation is much simpler, replacement of parts is less consuming of time and technique, and maintenance is easier to check and service during rest periods of associated equipment. It is a simpler project to effect transmission of energy between a rotating part and a relatively fixed part of the installation.

In practicing the invention of this disclosure, and in accomplishing the objects stated, there is provided an alternator or electric generator that is driven by the relative rotation of propeller hub and support, the output of the generator or alternator being led through appropriate conductors to each of the blade or air-foil heating sections in such manner that there will be equal energization of all of the heating elements. If the heating element of one section fails or works improperly, then the same effect is experienced by each of the other heating elements, which is of paramount importance where the several airfoil sections are designed to contribute to the balance or other predetermined conditions. It is only necessary to carry an electric source line through brushes; and slip; rings from the craft to the alternator or generator field, for its excitation and incorporate in that line suitable contacts for impulsing the icing control current equally to all airfoil sections. The conventional ships source of electric energy may then be carried to the field of the generator or alternator for excitation purposes. On the other hand, all brushes and slip rings may be eliminated by use of a small permanent magnet field generator for the alternator or generator exciting source. The energizing source generator can be mounted on the propeller so as to be driven by a gear fixed to the engine nose around the propeller shaft. The output of the energizing generator is then conducted through a cycling switch to the field of the icing control generator or alternator, whose output is in turn conducted to the blade elements.

With particular reference to- Figs. 1 and 2 of the drawings, l0, l2 and I4 refer to electric heating elements each mounted on a pitch shiftable propeller blade, which heating elements have a. ground or return connection at l6 and an ener gization connection I8 with the output of a generator or alternator 20, whose field winding 22 is energized by a current source 24 located in the ship or other support for the propeller, and under control of a switch 26 in a line 28 leading to a brush and slip ring 30 from which a line 32 traverses a pair of contacts 34 controlled by a cycling switch 36 actuated in response to operation of the generator, the contacts 34 also being connected with the generator field winding 22.

In the simplest form of installation, as shown or suggested by Figs. 2 and 4, the heating elements [0, l2 and [4 are connected in series relation by the lines 38, and 40, to ground I6 by 42 and to the energization line It. In the form. suggested by Figs. 1 and 3 the heating elements l0, l2 and I4 are each connected in parallel between the specific and individual ground It and the generator output I8 by lines 44, 4B and 48 respectively each of which connect with a transformer primary winding 50, 52 and 54 respectively, and thence by leads B, 58 and 60 respectively to the conductor I8. The primary windings 52, 54 and 50 are so disposed on the parallel legs 62, 64 of a. transformer core 66 that the flux generated in each le of the core member will be equally opposed by the other when all of the primaries are energized. One of the end members 68 of the transformer core is wound with a secondary winding '10 having a ground connection at l6 and joining a lead 12 connecting with an energizing winding 14 about a relay core 16 and grounded at l 6. Cooperable with the core 16 is an armature 78 operable to control separable contacts 80 interposed in the source line 32 to the generator field 22.

In all views of Figs 1 to 4, the cycling switch 36 comprises a cam member 82 engaging a lever 84 that is made to follow the contour of the cam by means of a spring 86 anchored to the supporting structure 88, the lever 84 insulatedly carrying one of the separable contacts 34. The cam member 82 is driven in timed relation with or by the generator 20, so that energization of the generator field 22 is periodically effected whenever the contacts 34 are closed. The periodic opening and closing of the contacts 34 effects a pulsing delivery of current from the generator 20 that is delivered through the connection l8 tothe blade heating elements in series and finally reaches ground at l6, with substantially equal energy impression upon all blade heating elements. In Figs. 1 and 3 the pulsating current from. [8 traverses the blade heating elements in parallel after traversing one of the transformer primaries and finally reaches ground 4 IS, with substantially equal energy impression upon all blade heating elements.

The equal energy impression for all blade heating elements is very important with respect to the installation of a rotatable structure such as on the blades of a rotating propeller. If one blade is heated at a different rate than the others, or if one blade is heated more than the others, or if there is any unequal heating of the blades of the group, then there will be a disproportionate icing control of the blades of the blade group. If the ice collects on the several blades of the group unequally, then the propeller assembly will be out of balance, and serious vibration will be present. As a result, all of the care, time and efiort of the manufacturer, and/ or Serviceman in carefully balancing the structure prior to flight, will be lost. The vibration introduced by the unequal icing control may result in the irreparable injury to the craft, or even its destruction.

In the scheme of Fig. 2 and Fig. 4 the equal energization of the blade heating elements is effected by connecting the blade heating elements in series between the generator output l8 and ground at 16 so that if there is a fault or break in the energization of one of the blade heating elements, then there will also be an interruption of current impression to all of the other blade heating elements. In the scheme of Figs. 1 and 3, the equal energization of the blade heating elements is effected by connecting the blade heating elements in parallel branches between the generator output and the ground, with a trans former primary winding in series each with a blade heating element. The transformer primary windings are so disposed on the core member 66 of the transformer that the fluxes developed in the core, when all blade heating elements are energized, will be equally opposed. In other words, the primaries 50 and 52 in series with elements [0 and [2 are arranged on the core leg 62 so that the flux developed thereby will be substantially equal to and oppose the flux developed in the leg 64 by the primary 54 in series with the element l4. Under those conditions there will be no flux in the end member 68 and hence no current generated in the secondary 10. However, if a break or other failure occurs in one of the parallel branches to the heating elements l0, l2 or 14, then there will be unequal flux development in the transformer core legs 62, E4 and a current will be developed in the secondary 10 which flows through 12 to relay winding 14 effecting movement of armature 18 to open the contacts in the source line to the generator field 22. Thus, upon the occurrence of any fault in one of the branches to the blade heating elements, current delivery to all of the blade heating elements is interrupted. Icing control for all of the blades of a propeller group is therefore equal, and there should be no disturbance of balance due to ice formation.

In the plans of Figs. 3 and 4, the field generator 20 is excited by other means than the usual ship source applied to the slip ring 30 by the battery 24. A permanent magnet field generator 25 has a rotor 21 in circuit with ground I6 and connected with lead 32 as in Fig. 3 where the field 22 is grounded, or as in Fig. 4 where the grounds for the rotor 21 and field winding 22 are connected by a common return conductor 29.

In the physical embodiment of the ice-controlling means in Figs. 5 to 8 inclusive, I00 refers to an aircraft structure from which extends a. propeller shaft I02 rotatable to the structure I00, and which mounts a hub I04 through theagenoy'of rear cones I05; interengaging splines I08 and'forward cone and nut-devices Ht. A rearwardly extending sleeve N2 of the hub is surrounded by a regulator plate II4 which is secured in driven relation by a sleeve nut I'IS, a cover member lI8 peripherally engaging the plate I I4 to form a reservoir I within which is' housed the fluid medium and mechanism-for pitch control of the propeller blades I22 which are journalledin sockets I24 radiating from the hub I04. The pitch control mechanism of the propeller includes a pump I26 mounted on the regulator plate II4, the pump having an inlet from the reservoir I20 and an outlet into the conduit I'28' leading to the control mechanism somewhat as disclosed in the patent to Blanchard et al. 2,307,102. The pump I20 provides a pinion I30 engaging a toothed flange I32 carried by an adapter sleeve I34. extending into the reservoir I20 in a manner to provide a fluid seal between the adapter sleeve and the plate H4 and cover II8 through the use of bearings andseals at and I38;

The adapter sleeve is part of a composite structure that includes a ring [40 secured thereto byscrew devices I42, and a flange plate I44 secured by screw devices I46; the flanged plate 5%4' having a lug I48engageable in a notch I50 providedby a clip I52 secured to the structure 100 such that the adapter assembly is held rela tively fixed while the reservoir and propeller parts are rotatable relative to the adapter assembly and relative to the structure I530. The flanged plate provides a cylindrical ring I54 surrounding a rearward extension of the cover memher I I8 and at one point supports an insulating block I56 carrying. stationary brushes I58 and I60. The stationary brush I58 engages a rotatable collector ring I62 corresponding to the collector ring 30. shown'in Figs. 1' and 2; A rotatablesecond slip ring I64 is engaged by the stationary' brush I60 and is used in a physical embodiment to provide the ground connection IB'indicated in Figs. 1 and 2 for each of theel ments. there suggested. Connecting with the slipring I 62' there is a lead 32 that traverses a passage I66 in the cover member IE8 and passes'through the plate H4 on its way to connect with the generator by means of a terminal post I68. Joined to the slip ring. I541there is a second lead I10 that passes. through the electric elements. in a similar manner while the leadlil communicates with a brush I58 and'a lead'll2 connects with a brush I60 for grounding purposes.

The toothed flange I32 in addition to acting as a driving member for the pump gear I30 also drives an idler pinion I14 that in turn meshes with a pinion I16 secured to a tubular shaft I30'having a driving connection with a shaft element I82 extending forward and through the plane of rotation of the propeller to support a pulley I84 about which is trained an endless belt I85 and thence a variable diameter pulley I08 on the shaft I90 of the generator '20. Asshown in Fig. 6 the shaft element I80" has. be'aringsat. each end. in a boss I'92'secured to the regulator plate H4, and the shaft I80 has a splined engagement at I94 with the shaft element I82 which in turn has driving engagement with a tubular shaft I05 extending to the pulley I84 which is pinned thereon at I98. A tubular sheath 200 is in closing relation with the shaft- I96-',- it being sock'eted in the plate I I4 and piloted upon a shell member 202 secured to the generator end frame 204'; the latter of which supports an anti-friction bearing 205 for the shaft I96 and its pulley I84. A shell member 200 encloses the pulley I84, the belt I36 and the pulley I88 and is secured to the generator end frame 204 by appropriate screw devices such as 2 I 0, thus enclosing all of the gear transmission elements from the pinion I16, the shaft I98, pulley I84, belt I85, and pulley I08.

The generator shaft I is of tubular form and is supported in an anti-friction bearing 2I2 supported by the generator end plate 204 while the shell member 208 is apertured and flared inwardly at 2I4 to provide an air intake in registry with a bore Zlt of the generator shaft I90 the other end of which supports an impeller 2I8 and is journalled in an anti-friction bearing 220 sup-'- ported by an end frame 222 mating with a generator frame 224. A plug member 226 closesone end of the tubular shaft I90 and latter opening 228 open the bore 2I6 of the generator shaft to the outside thereof such that air entering the aperture 2I4 of the shell and passing along the bore 2I6 of the shaft may pass thru 228 assisted by the impeller 2I8 to be blown against the field winding 230 and the rotor 232 of the generator. The field laminations 234 are appropriately notched at 235 to provide for actual flow of the air thru the assembly of the generator such that it may blow out through an aperture 233 in the end frame 204. The generator frame is secured to a flanged ring 240 by which the generator is mounted coaxially of the shaft I02 by means of screw devices 242 passing through the flange 240 a shim 244, a spacer 246 and a flange 240a to be threaded into the face of the hub I04.

It was pointed out that the lead 32 of the field winding was secured to an insulated terminal stud I68, which terminal stud is secured to the generator frame 224 and has a lead 240 connected therewith and passing thru the notch v238 of one of the field laminations to connect with a terminal post 250 supported by the cycling switch 36 shown in Fig. 5 by the dot and dash rectangle. From-the cycling switch 36 the return lead 252 communicates with the field .winding 230 which in turn emanates with the appropriate number of leads 254 joined to terminal posts 250 also mounted in the generator frame 224 and from which the appropriate leads such as 56 lead to the respective transformer primary windings as has been described with respect to Figs. 1 and 2, but which transformer structure has not been illustrated in the physical embodiments.

From the transformer primary winding a lead 258 is secured to a terminal member 200, as shown in Figs. 5- and '7, supported by an insulated bushing 252 that extends through the flanged ring 242. the shim 244, the spacer 246, the flange 240a and the wall of the socket I24 to end in a brush member 234 inside of the socket I24. The brush 254 is in the form of a bow spring of an arc of considerably less radius than that of the blade root of the propeller and is such that its end portions 266 are biased to engage the collector ring 268 secured to theblade not 210 by means of an insulating ring 272 interposed therebetween. The nut 210 is threaded upon the inward end 214 of the blade where it is locked by a pin 216 that prevents its removal, the nut engaging a stack of antifriction bearings 218 whose thrust is received by a retaining ring 200 threaded in the open end of the socket I24; The collector ring 286 provides a tab or lug 282 to which is connected a lead 28-4 lodged in a bore or drill way 286 in the wall of the member 214 so that the electric lead 284 may pass outwardly between the shank I22 and a fluid operated torque unit 288 to join a terminal post 258 located in the wall of the shank I22 and to which the connection 44, 46 or 48 may be joined leading to the blade heating element.

In mounting the generator coaxially of the shaft I02 it is socketed within the hub structure I04 to such an extent that a pilot portion 292 pilots within a ring 294 secured within the hub to close off control passages 296 and 298 communicating with the conduit I28 of the regulator plate and the torque unit 288 for control of pitch of the propeller blade. On the end of gen erator shaft I90 there is provided a spur gear 388 affording drive of the movable parts of the cycling switch 38 so that operation of the generator rotor will also effect a periodic operation of the cycling switch thus periodically applying the current source coming thru the lead 32 and 248 in the form of pulses to the field 230 of the generator. The generator output is delivered in pulses thru the leads 56 and eventually thru leads 258 to the terminals 268, brush 2'54, and collector ring 268 and by the leads 284 to the blade heating elements. It will thus be observed that rotation of the propeller structure including the regulator plate H4 and its cover IIB about the adapter assembly I34 will not only drive the pump I28 for supply of fluid under pressure to effect pitch control of the blades, but will also effect rotation of the pinion I76 and the gear train connected therewith to the generator pulley I88 which effects rotation of the rotor 232 and the operation of the cycling switch 36. If the manual control switch 26 is closed then the generator will be so energized that its output will be equally delivered or distributed to all of the blade heating elements of the propeller assembly.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, 15

it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a rotating aircraft propeller, a plurality of blades in the propeller, electric heating elements carried by each of the blades for control of ice formation thereon, an electric generator driven in response to propeller rotation for supplying energy to the blade heating elements, a source of electric energy from without the propeller for energizing the field of the generator, means driven in timed relation with the generator for pulsing the field excitation of the generator, means connecting the output of the generator with the blade heating elements including a primary transformer winding in series with each heating element, a transformer having a core member threading each primary winding, means disposing the transformer windings so as to effect equally opposed flux impression in the core when all heating elements are energized, a secondary winding disposed on said core member, a relay winding serially connected with the transformer secondary and constructed and arranged to be energized when one of the blade heating elements fails to be equally energized from the generator, a pair of separable contacts in the energy source to the generator field constructed and arranged to be opened by the relay winding for interrupting energization of the generator field whenever the generator fails to equally energize all or the heater elements.

2. In an aircraft propeller rotatable relative to a support, a hub having a plurality of blades therein, electric heating elements secured to each blade for control of ice formation thereon, a generator carried by the hub and rotatable relative to the hub in response to rotation of the hub relative to the support for supplying energy to the blade heating elements, means connecting the output of the generator to each of the heating elements including a serially connected transformer primary winding, said transformer having a core member providing a pair of parallel limbs each supporting an equal number of primary turns and each leg magnetically opposed to the other so as to effect equally opposed fiux impressions in the core when all heating elements are energized, a bridge member provided by the core magnetically linking the said legs, a. secondary winding disposed on the bridge memher in inductive relation with the transformer primary windings, a relay with contacts and having an energizing coil serially connected with the transformer secondary, means providing a current source from the support to the field winding of the generator and passing through the said relay contacts, a cycling switch operable in response to propeller rotation for interrupting the source current to the generator field and means including the generator and cycling switch for supplying current to the heating elements in reoccurring pulses equally to each blade element, the transformer effecting opening of the relay contacts coincident to failure of electric energy to one of the electric heating elements.

3. In an aircraft propeller rotatable relative to a support, a hub having a plurality of blades therein, electric heating elements secured to each blade for control of ice formation thereon, a generator carried by the hub and operable in response to rotation of the propeller relative to the support for supplying energy to the blade heating elements, means providing a field circuit for the generator extending from a current source on the support, a cycling switch having separable contacts interposed in the field circuit and constructed and arranged to periodically energize the generator field, a transformer having a plurality of primary windings arranged in flux balancing relation on a core member and each serially connected between the generator output and a blade heating element, and means including the generator and cycling switch for supplying energy equally to all of the blade elements in pulses as determined by the cycling switch, a pair of relay contacts in the generator field circuit, and means including a secondary winding of the transformer for opening the relay contacts upon unequal energy supply to the blade heating elements.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 397,340 Cohen Feb. 5, 1889 818,424 Eastman Apr. 24, 1906 1,346,164 Bennett July 13, 1920 1,776,130 Petch Sept. 16, 1930 2,429,061 Hunter Oct. 14, 1947 2,444,557 Eaton July 6, 1948 2,466,238 Hoof Apr. 5, 1949 FOREIGN PATENTS Number Country Date 585,556 Great Britain Feb. 11, 1947 

